Preheat oven to 375°F. Grease a 9"x13" baking dish with a little butter. Combine pumpkin puree, evaporated milk, sugar, eggs and spices in a large bowl and whisk to combine.
15 ounce can pumpkin puree, 12 ounce can evaporated milk, 1½ cups sugar (granulated), 3 eggs, 2 teaspoons cinnamon, 2 teaspoons pumpkin pie spice
Pour pumpkin mixture into buttered baking dish. Sprinkle the yellow cake mix over the pumpkin mixture, spreading it as evenly as possible.
15.25 ounce box Yellow Cake Mix
Pour melted butter over the cake mix, covering as much of the cake as you can. If some spots need more coverage, melt more butter.
1 cup unsalted butter
Evenly spread the top with chopped pecans.
1 cup pecans
Bake 50 minutes to 55 minutes, or until the cake is cooked through. The cake should be a nice browned color and mostly firm, but the middle should remain soft. Remove from oven, and serve hot or cold with ice cream or whipped cream.
Mix 1 cup of ready made or homemade whipped cream with 1 tablespoon of pumpkin spice and mix well. Refrigerate and serve on top of the pumpkin cake.
1 Tablespoon pumpkin pie spice, 1 cup whipped cream